Electrical power is supplied to rural America using three-phase electrical power transmitted over three conductors. In order to minimize the cost of supplying electrical power to these rural areas, the physical earth is used as a return path for the imbalances in electrical power. While functional for its intended purpose, the use of the physical earth as the return path for the three-phase electrical power has resulted in certain unforeseen effects on livestock. More specifically, the energy flowing through physical earth has been found to have a detrimental effect on the feeding habits and milking of livestock, as well as, pregnant livestock and their young.
Compounding the problems associated with the use of physical earth as a return path for the imbalances in electrical power, in order to save costs and conserve energy, farmers have begun utilizing variable frequency drives to power the various motors and equipment utilized on their farms. These variable frequency drives allow a farmer to vary the electrical power supplied to the motors and equipment utilized on the farm, thereby resulting in a significant amount of energy savings for both the farmer and the electrical co-generation facility. However, it has been found that the phase waveforms supplied by the variable frequency drive are not identical at any given time. By transmitting these phase waveforms, common mode noise, and associated phenomenon over the conductors, additional stray currents flow through the physical earth. As heretofore described, these stray currents flowing through the physical earth may cause adverse effects on the livestock maintained on the farm. In view of the foregoing, it can be appreciated that it is highly desirable to minimize the flow of stray currents through the physical earth.
Therefore, it is a primary object and feature of the present invention to provide a method of transmitting three-phase electrical power from a power source to a target.
It is a further object and feature of the present invention to provide a method of transmitting electrical power that minimizes the leakage of common mode noise, associated phenomenon, and stray currents associated therewith.
It is a still further object and feature of the present invention to provide a method of transmitting electrical power that is simple to implement.
It is a still further primary object and feature of the present invention to provide a method of transmitting electrical power that minimizes the effects of such transmission on livestock in close proximity thereto.
In accordance with the present invention, a method is provided to reduce the stray noise associated with the transmission of electrical power between a power source and a target. The method includes the steps of interconnecting the power source and the target with a conductor and positioning a shield about the conductor to prevent electromagnetic and radio frequency interference from passing therethrough. A low impedance path is provided for the stray noise to travel between a neutral point of the power source and the target.
The target is isolated from ground and includes a grounding block that is, in turn, interconnected to the neutral point of the power source with a ground wire. The neutral point of the power source is interconnected to ground. In order to provide a low impedance path, a wire braid is wrapped around the shield. The wire braid has first and second ends. The first end of the wire braid is interconnected to the target and the second end of the wire braid is interconnected to the neutral point of the power source.
In accordance with the further aspect of the present invention, a method is provided to reduce the stray noise associated with the transmission of electrical power between a power source and a target. The method includes the steps of isolating the target from ground and providing a conduit. The conduit includes a conductor, a tubular core, braiding and a flexible outer jacket. The conductor electrically connects the power source and the target. The tubular core extends about the conductor and has the outer surface. The braiding is wound about the outer surface of the core and the flexible outer jacket extends about the braiding. A first end of the conductor is interconnected to the power source and the second end of the conductor is interconnected to the target. The first end of the braiding is interconnected to a neutral point of the power source and a second end of the braiding is interconnected to a grounding block on the target.
The neutral point of the power source is interconnected to ground. In addition, the neutral point of the power source is interconnected to the grounding block of the target with the ground wire. The ground wire may be wrapped around the conductor or positioned adjacent the conductor along the entire length thereof. The braiding may include first and second end portions that extend through the outer jacket of the conduit. The outer jacket also includes first and second ends. Connectors may be mounted on the core adjacent corresponding ends of the outer jacket.
In accordance with a still further aspect of the present invention, a method is provided to reduce the stray noise associated with the transmission of electrical power between a power source and a target. The method includes the step of transmitting electrical power from the power source to the target. A low impedance path to a neutral point of the power source is provided for the stray noise associated with the transmission of the electrical power.
The power source and the target are interconnected with a conductor such that the electrical power is transmitted thereon. A shield may be positioned about the conductor to prevent electromagnetic and radio frequency interference from passing therethrough. In order to provide the low impedance path, wire braiding is wrapped about the shield. The wire braiding has first and second ends. A first end of the wire braiding is interconnected to the target and a second end of the wire braiding is interconnected to the neutral point of the power source.
It is contemplated to isolate the target from ground and to interconnect the neutral point of the power source to ground. The target includes a grounding block that may be interconnected to the neutral point of the power source with a ground wire. The ground wire may be wrapped around the conductor or positioned adjacent thereto.